The present invention relates to an axial braking device for arresting a relative movement between a bearing unit or assembly, and a shaft member slidably engaging the bearing assembly and movable axially thereof relative to the bearing assembly.
In various fields of art, it is frequently required to arrest or stop a shaft, rod or similar body, during its movement along its axis, at a predetermined position along the axis. A typical example of a member having such an axially moving body is an air cylinder which uses air as a working fluid. As the air is compressible, a piston rod of the cylinder can not be stopped instantaneously when the supply of air under pressure is cut off, and consequently can not be accurately located at the desired position. In view of this fact, it has been commonly practiced in the art to use a fixed stop which is adapted to abut on the piston rod or a suitable member fixed to the piston rod, and thus stop the piston rod at an intended position with considerably high positioning accuracy. However, the positioning by use of such stop means suffers a difficulty of changing, as desired, the position at which the moving member is to be stopped. Thus, there has been a need for arresting an axially moving member exactly at a desired position along the axis. This need also exists for many other purposes. For example, in an arrangement wherein a carriage is moved while being guided by a stationary guiding rod or rods, it is needed to apply a brake for stopping a relative movement between the carriage and the guiding rods so that the carriage is positioned at a selected position as if it were fixed integrally to a base frame to which the guiding rods are secured.